//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

// <forward_list>

// template <class Predicate> void      remove_if(Predicate pred); // C++17 and before
// template <class Predicate> size_type remove_if(Predicate pred); // C++20 and after; constexpr since C++26

#include <forward_list>
#include <iterator>
#include <cassert>
#include <cstddef>
#include <functional>

#include "test_macros.h"
#include "min_allocator.h"
#include "counting_predicates.h"

template <class L, class Predicate>
TEST_CONSTEXPR_CXX26 void do_remove_if(L& l, Predicate pred, typename L::size_type expected) {
  typename L::size_type old_size = std::distance(l.begin(), l.end());
#if TEST_STD_VER > 17
  ASSERT_SAME_TYPE(decltype(l.remove_if(pred)), typename L::size_type);
  assert(l.remove_if(pred) == expected);
#else
  ASSERT_SAME_TYPE(decltype(l.remove_if(pred)), void);
  l.remove_if(pred);
#endif
  assert(old_size - std::distance(l.begin(), l.end()) == expected);
}

TEST_CONSTEXPR bool g(int i) { return i < 3; }

struct PredLWG526 {
  TEST_CONSTEXPR_CXX20 PredLWG526(int i) : i_(i) {}
  TEST_CONSTEXPR_CXX20 ~PredLWG526() { i_ = -32767; }
  TEST_CONSTEXPR bool operator()(const PredLWG526& p) const { return p.i_ == i_; }

  TEST_CONSTEXPR bool operator==(int i) const { return i == i_; }
  int i_;
};

TEST_CONSTEXPR_CXX26 bool test() {
  {
    typedef int T;
    typedef unary_counting_predicate<bool (*)(T), T> Predicate;
    typedef std::forward_list<T> C;
    const T t1[] = {0, 5, 5, 0, 0, 0, 5};
    const T t2[] = {5, 5, 5};
    C c1(std::begin(t1), std::end(t1));
    C c2(std::begin(t2), std::end(t2));
    Predicate cp(g);
    do_remove_if(c1, std::ref(cp), 4);
    assert(c1 == c2);
    assert(cp.count() == static_cast<std::size_t>(std::distance(std::begin(t1), std::end(t1))));
  }
  {
    typedef int T;
    typedef unary_counting_predicate<bool (*)(T), T> Predicate;
    typedef std::forward_list<T> C;
    const T t1[] = {0, 0, 0, 0};
    C c1(std::begin(t1), std::end(t1));
    C c2;
    Predicate cp(g);
    do_remove_if(c1, std::ref(cp), 4);
    assert(c1 == c2);
    assert(cp.count() == static_cast<std::size_t>(std::distance(std::begin(t1), std::end(t1))));
  }
  {
    typedef int T;
    typedef unary_counting_predicate<bool (*)(T), T> Predicate;
    typedef std::forward_list<T> C;
    const T t1[] = {5, 5, 5};
    const T t2[] = {5, 5, 5};
    C c1(std::begin(t1), std::end(t1));
    C c2(std::begin(t2), std::end(t2));
    Predicate cp(g);
    do_remove_if(c1, std::ref(cp), 0);
    assert(c1 == c2);
    assert(cp.count() == static_cast<std::size_t>(std::distance(std::begin(t1), std::end(t1))));
  }
  {
    typedef int T;
    typedef unary_counting_predicate<bool (*)(T), T> Predicate;
    typedef std::forward_list<T> C;
    C c1;
    C c2;
    Predicate cp(g);
    do_remove_if(c1, std::ref(cp), 0);
    assert(c1 == c2);
    assert(cp.count() == 0);
  }
  {
    typedef int T;
    typedef unary_counting_predicate<bool (*)(T), T> Predicate;
    typedef std::forward_list<T> C;
    const T t1[] = {5, 5, 5, 0};
    const T t2[] = {5, 5, 5};
    C c1(std::begin(t1), std::end(t1));
    C c2(std::begin(t2), std::end(t2));
    Predicate cp(g);
    do_remove_if(c1, std::ref(cp), 1);
    assert(c1 == c2);
    assert(cp.count() == static_cast<std::size_t>(std::distance(std::begin(t1), std::end(t1))));
  }

  { // LWG issue #526
    int a1[] = {1, 2, 1, 3, 5, 8, 11};
    int a2[] = {2, 3, 5, 8, 11};
    std::forward_list<PredLWG526> c(a1, a1 + 7);
    do_remove_if(c, std::ref(c.front()), 2);
    for (std::size_t i = 0; i < 5; ++i) {
      assert(!c.empty());
      assert(c.front() == a2[i]);
      c.pop_front();
    }
    assert(c.empty());
  }

#if TEST_STD_VER >= 11
  {
    typedef int T;
    typedef unary_counting_predicate<bool (*)(T), T> Predicate;
    typedef std::forward_list<T, min_allocator<T>> C;
    const T t1[] = {0, 5, 5, 0, 0, 0, 5};
    const T t2[] = {5, 5, 5};
    C c1(std::begin(t1), std::end(t1));
    C c2(std::begin(t2), std::end(t2));
    Predicate cp(g);
    do_remove_if(c1, std::ref(cp), 4);
    assert(c1 == c2);
    assert(cp.count() == static_cast<std::size_t>(std::distance(std::begin(t1), std::end(t1))));
  }
  {
    typedef int T;
    typedef unary_counting_predicate<bool (*)(T), T> Predicate;
    typedef std::forward_list<T, min_allocator<T>> C;
    const T t1[] = {0, 0, 0, 0};
    C c1(std::begin(t1), std::end(t1));
    C c2;
    Predicate cp(g);
    do_remove_if(c1, std::ref(cp), 4);
    assert(c1 == c2);
    assert(cp.count() == static_cast<std::size_t>(std::distance(std::begin(t1), std::end(t1))));
  }
  {
    typedef int T;
    typedef unary_counting_predicate<bool (*)(T), T> Predicate;
    typedef std::forward_list<T, min_allocator<T>> C;
    const T t1[] = {5, 5, 5};
    const T t2[] = {5, 5, 5};
    C c1(std::begin(t1), std::end(t1));
    C c2(std::begin(t2), std::end(t2));
    Predicate cp(g);
    do_remove_if(c1, std::ref(cp), 0);
    assert(c1 == c2);
    assert(cp.count() == static_cast<std::size_t>(std::distance(std::begin(t1), std::end(t1))));
  }
  {
    typedef int T;
    typedef unary_counting_predicate<bool (*)(T), T> Predicate;
    typedef std::forward_list<T, min_allocator<T>> C;
    C c1;
    C c2;
    Predicate cp(g);
    do_remove_if(c1, std::ref(cp), 0);
    assert(c1 == c2);
    assert(cp.count() == 0);
  }
  {
    typedef int T;
    typedef unary_counting_predicate<bool (*)(T), T> Predicate;
    typedef std::forward_list<T, min_allocator<T>> C;
    const T t1[] = {5, 5, 5, 0};
    const T t2[] = {5, 5, 5};
    C c1(std::begin(t1), std::end(t1));
    C c2(std::begin(t2), std::end(t2));
    Predicate cp(g);
    do_remove_if(c1, std::ref(cp), 1);
    assert(c1 == c2);
    assert(cp.count() == static_cast<std::size_t>(std::distance(std::begin(t1), std::end(t1))));
  }
#endif

  return true;
}

int main(int, char**) {
  assert(test());
#if TEST_STD_VER >= 26
  static_assert(test());
#endif

  return 0;
}
